1. Field of the Invention
The present invention relates to a medical apparatus equipped with a treatment instrument to be inserted into a lumen of a subject to carry out treatment, and more particularly to a medical apparatus which aids a treatment instrument insertion operation using virtual endoscopic images based on three-dimensional image data of the lumen.
2. Description of the Related Art
In recent years, diagnosis and treatment have come to be carried out widely using three-dimensional image data. For example, three-dimensional images inside a subject are obtained by picking up tomograms of the subject using an X-ray CT (Computed Tomography) apparatus and used to carry out diagnosis and the like of a target site.
The CT apparatus performs successive scans (helical scans) of the subject continually while rotating X-ray irradiation position and detection position continuously by moving the subject. Then, three-dimensional image data is obtained from a large number of successive two-dimensional tomograms of the subject.
Examples of the three-dimensional image data used for diagnosis and treatment include three-dimensional image data of the bronchi of the lungs. The three-dimensional image data of the bronchi of the lungs is used, for example, to three-dimensionally locate an abnormal site where lung cancer is suspected. Then, to check the abnormal site by a biopsy, an endoscope is inserted into the bronchi, a treatment instrument such as a biopsy needle or biopsy forceps is protruded from a distal end portion of the endoscope, and a sample is taken from the target site.
In a lumen having a plurality of bifurcations, such as a bronchus, it is sometimes not easy to insert a treatment instrument precisely into a target site in the lung in a short time. Thus, for example, Japanese Patent Application Laid-Open Publication No. 2009-56238 discloses a navigation system which forms three-dimensional images of a lumen based on three-dimensional image data of the subject, determines a route to a target spot along the lumen using the three-dimensional images, further forms and displays virtual endoscopic images of the lumen along the route, and thereby guides insertion operation.
Also, to assist insertion operation, Japanese Patent Application Laid-Open Publication No. 2002-119507 discloses a medical apparatus which displays a virtual image viewed from a distal end portion of a catheter inserted in a subject while Japanese Patent Application Laid-Open Publication No. 2002-306403 discloses an endoscope apparatus which displays a virtual image of a distal end portion of an endoscope in superimposition on a virtual endoscopic image.